Ecotropic type C viruses, isolated from wild mice in Southern California, produce a Non T cell splienic lymphoma and a neurodegenerative paralytic disease in susceptible inbred and wild mice. In this study we propose to investigate the mechanism of virus induced damage of the spinal motorneurons in mice. Our approach to this longterm goal includes (a) studies on mechanism of these virus replication in central nervous system of mice, (b) determination of correlation of viral gene expression and pathogenicity, and (c) studies on the role of subvirion components in neuronal injury. The major analytical techniques which will be used in this study are nucleic acid hybridization, radioimmuno assay, receptor binding assay immunofluorescent and immunoperoxidase staining, etc.